Minor fixes in per channel support for qconv kernel (#25182)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/25182
Removing empty line, an unused variable and adding a check for supported quantized data types.
ghstack-source-id: 89293181
Test Plan: buck test mode/dev caffe2/test:quantized -- --print-passing-details
Reviewed By: jianyuh
Differential Revision: D17052234
fbshipit-source-id: dbe470f0cd73fa4fca44bd15424adbaf7ceca469
